Debra Patla holds a young spotted frog at Indian Pond. Patla helps lead surveys of amphibian life throughout Yellowstone and Grand Teton national parks. “What they do with their lives is so different than what we can even imagine,” she said. “They’re totally foreign.” (Photo: TRIBUNE PHOTO/KRISTEN INBODY)

For more than 20 years, Patla has surveyed amphibian life in Yellowstone wetlands. She works closely with Ray of the National Park Service's Greater Yellowstone Inventory & Monitoring Network and scientists with the U.S. Geological Survey's Amphibian Research and Monitoring Initiative to monitor amphibians annually.

Amphibian research in Yellowstone National Park

'So charismatic'

As Ray and Patla mucked through the pond, the squish under their boots and the caw of ravens was the only sound.

"I've gotten chased out of this spot by bison many times," Patla said.

"You have to remind yourself you're in Yellowstone and look up occasionally," Ray added.

The shallow fringes of the pond were black with wiggling tadpoles. Since the early 1900s, boreal toads have been documented in Indian Pond. Patla has seen them every year since she started her surveys in 1993.

"This is perfect for a frog: warm, moist, humid," Patla said. "The pond has been shrinking every year, so I don't know what the forecast will be."

Indian Pond formed in the crater of a hot springs just off Yellowstone Lake. It's one of only a handful of monitored places in Yellowstone or the Grand Tetons where signs of toad breeding are reliably found.

The water is shrinking away from the side of the pond with thermal features that keep the water warm, though. Ray said tadpoles favor the warmest parts of the pond, even if the water is only a few inches deep. That can leave them stranded, as water recedes.

In 10 minutes, she and Ray spotted six frogs and then a toad.

Historically, Yellowstone and Grand Teton had six species of native amphibians. One species, the northern leopard frog, apparently has disappeared from Grand Teton and has not been seen in decades. A spadefoot species has been documented infrequently in Yellowstone over the last century.

The remaining native species, the Columbia spotted frog, the boreal chorus frog, the barred tiger salamander and the boreal toad are relatively widespread. Grand Teton also is home to one non-native amphibian species, the American bullfrog.

"One of the neat things about our four species is they represent a lot of diversity," Patlas said. "It's very satisfying in its natural history breadth."

Tadpoles in Indian Pond, Yellowstone National Park(Photo: TRIBUNE PHOTO/KRISTEN INBODY)

Amphibians in peril

Across the country, amphibian populations shrink by an average of 4 percent a year.

Globally, habitat destruction, changes in land use, climate change and amphibian disease — and likely a combination of those factors — have put a third of the species into threatened status, with another 43 percent declining. According to AmphibiaWeb, extinctions of at least 168 of the about 7,000 known amphibian species worldwide has occurred in just the past two decades.

"When the amphibian decline started nationwide, people had to think through how to study that," Palta said. "The nation's herpetologists — who could fit in a bathroom together — got together."

The result was a project surveying federal lands across the country looking for amphibians, using those sites to learn about the whole picture of amphibian life.

"There were a lot of places they didn't even know what species were there," Patla said.

Combined, Yellowstone/Grand Tetons represent one of the largest annual amphibian monitoring areas. With the inclusion of John D. Rockefeller Jr. Memorial Parkway, these parks represent an area about the size of Connecticut.

Ray said the surveys in Yellowstone focus on the wetlands but consider the contributions of snow and runoff from the areas around them. While Yellowstone hasn't seen the same declines as the rest of the country, researchers have witnessed the drying of wetlands over the last few decades, a trend that could impact local amphibian life.

Since the last Ice Age, the park's amphibians have been working their way up to higher elevations, though 9,000 to 9,500 feet may be the upward limit in this region. Amphibians need surface water available long enough for them to breed, hatch, grow, and, ultimately, metamorphose.

"You see a lot of variability, from the (Yellowstone) Northern Range to the forests to the Yellowstone River headwaters to open wet meadows," he said.

In Yellowstone and Grand Tetons, wetlands with standing water are better amphibian breeding habitat than streams and rivers. Tiger salamanders and boreal chorus frogs need water shallow enough for vegetation to grow, on which they attach their eggs. Big lakes, like Yellowstone Lake, stay too cold for tadpole development. On the other extreme, some thermal areas are too hot.

"Some places are just too dry or too steep to hold water," Patla said. "A lot of wetlands don't last long enough, especially in a dry year."

Because Palta and GRYN have studied Yellowstone amphibians for so long, they've amassed enough data that patterns have begun to emerge. For example, the relation of wetlands to weather patterns, and the differences in breeding between hot and cool years, flood years and drought years has emerged.

Lately, wetlands that were permanent have become seasonal. This year, though, was nice and wet, and amphibians were in abundance, including in some places they hadn't been seen before or recently.

Comparing recent findings with places where amphibians were noted by a ranger in the 1950s, researchers found all four wide-spread species. A spadefoot species has been only rarely seen over the last century, however, spadefoots were documented by Yellowstone biologists in 2013 and another population is present just outside of Yellowstone near Hebgen Lake. Northern leopard frogs haven't been documented since the 1950s, barring a tourist's sighting in the 1990s.

"Maybe they're still lurking somewhere," Palta said.

Spadefoot toads, which come up after rains, maybe only for a day, have been seen a handful of times but not by the monitoring project.

The ranger spent multiple years cataloging amphibians. In the 1950s, boreal toads were described as common. Now they are "still here but really localized."

"I came along in the 1990s to redo this survey, and only 20 percent of the sites he found were as described," Palta said. "The main study areas dwindled away."

In Yellowstone, the problems have come from seemingly minor changes.

"It was all the little things people did, pumped water for use, more people and traffic, wetlands filled in, a highway moved," Palta said. "Then disease came, and there were several die-offs."

"You don't get those reports of thousands of salamanders anymore," he said.

On an 1863 trip to what would become Yellowstone, Captain Walter DeLacy described thousands of salamanders swarming his campfires, often killing themselves in the hot ash and flames.

"There seemed to be no end to their number ... They continued to annoy us all night, getting into our blankets, and making themselves generally unpleasant until morning," he wrote, as quoted in "Amphibians & Reptiles of Yellowstone and Grand Teton National Parks" by Edward D. Koch and Charles D. Peterson.

The monitoring suggests amphibian occupancy is relatively stable, with signals that may be related to climate change. More hotter, dryer years are expected and the higher elevations are warming faster.

The more isolated a population becomes, the harder a population rebound becomes. Isolated populations are susceptible to rapid declines and even blinking out altogether. A cluster of wetlands may be more effective at supporting amphibians across a range of conditions or during other stressful times.

"Some days I think they'll outlive us," Patla said. "They've been through so many changes, but extinction rates are high for amphibians."

Debra Patla and Andrew Ray monitor amphibian life at Indian Pond in Yellowstone National Park. They both became fascinated with amphibians as children .(Photo: TRIBUNE PHOTO/KRISTEN INBODY)

Counting and cataloging

The six to 14 researchers in the project every year get up early each day for their surveys and put their equipment together — with nets, waders, GPS units, computers to record data, a camera, a thermometer, a weather monitor, maps, photographs of the area to be monitored, a clipboard, extra batteries, bear spray, a radio, a spot beacon, a research permit and lunch.

Reaching a site may take two hours or two days. Biologists head for the field in pairs, one surveying and one recording data. After the first surveyor is finished they swap responsibilities producing two independent surveys at each site.

"Some say it changes their lives to spend time in the wild," Patla said. "People like to go out and see amphibians — until the mosquitoes start biting."

Once field season is over, crunching the numbers begins. Ray works closely with a statistician and other researchers to consider trends and factors in the patterns of breeding.

As Ray and Patla made their way around Indian Pond, they walked, looked, and every three steps, dip their nets.

By this time in summer, tadpoles are getting hard to find. The survey period is compressed from June to July. While amphibians are present all year, what biologists look for are signs of breeding activity like eggs and tadpoles. Additionally, adults are mobile and hard to find compared to eggs and tadpoles which are restricted to flooded wetlands.

The eggs hatch about two or three weeks after they are deposited and then in another month to six weeks the tadpoles metamorphose into frogs with an awkward "teenage" phase of leg growing.

"If you see eggs, tadpoles or metamorphs, you known there was successful breeding," Ray said.